The Pegasus sank in 50 feet of water in Lynn Canal shortly before 11:35 a.m. in Sunshine Cove, off Mile 35 of Glacier Highway. The ship was transporting blasting caps that require "a high-impact ignition," Lane said.

Two people were on board when the Pegasus capsized. They escaped with no injuries, Lane said.

Video from the Air of Ship

Ship hull and containers

Gumption Leasing, a Juneau company with an office in Auke Bay, owns the Pegasus, Lane said. The company did not return phone calls Tuesday night.

Officials said an excavator also was lost overboard during the incident.

Lane said the ship was headed to an unknown work site, but he did not know the ship's origin or destination.

Local mine officials could not be reached.

Investigators were expected on scene early Tuesday evening. The investigation would take weeks, Lane said.

The Coast Guard said it was posting a patrol boat at the scene to provide security until either the explosives were recovered or Gumption Leasing provided security.

Trucano Construction has been contracted to recover the explosives and the vessel.